<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8">
    <title>Document</title>
  </head>
  <body>
    <script>
      function Person() { }
      Person.prototype = {
        constructor: Person,                   // 手动指向Person构造函数
        sayHello: function () {
          console.log('hello');
        }
      };
      var p1 = new Person();
      console.log(p1.constructor === Person); // 输出结果：true
    </script>
  </body>
</html>